You're not considering the cost of obtaining this information. And plenty of reviews that I read contained information on the lifespan (usually in the form of "this broke! zero stars!")
And "it broke" just tells me it has a very short lifespan, but won't let me know if some stuff has a 6 months vs 6 years lifespan. "short lifespan" is fundamentally different from "not working".
We're used to the former (unfortunately), but won't consider the latter acceptable, except maybe when buying obviously overly cheap stuff